Laboratory and field evaluation of MAA, an ointment containing N,N-diethyl-3-methylbenzamide (DEET) against mosquitoes in Burkina Faso

BACKGROUND: Malaria vector control relies upon the use of insecticide-treated nets and indoor residual spraying. However, as the emergency of insecticide resistance in malaria vectors grows, the effectiveness of these measures could be limited. Alternative tools are needed. In this context, repellents can play an important role against exophagic and exophilic mosquitoes. This study evaluated the efficacy of MAA, a novel repellent ointment, in laboratory and field conditions in Burkina Faso. METHODS: For laboratory and field assessment, 20 volunteers were enrolled and trained for nocturnal collection of mosquitoes using human landing catches (HLC). In the laboratory tests, 2mg/sq cm of treatment (either MAIA or 20% DEET) were used to assess median complete protection time (CPT) against two species: Anopheles gambiae and Aedes aegypti, following WHO guidelines. For both species, two strains consisting of susceptible and local strains were used. The susceptible strains were Kisumu and Bora Bora for An. gambiae and Ae. aegypti, respectively. For the field test, the median CPT of MAA was compared to that of a negative (70% ethanol) and positive (20% DEET) after carrying out HLCs in rural Burkina Faso in both indoor and outdoor settings. RESULTS: Laboratory tests showed median Kaplan-Meier CPT of 6h 30min for An. gambiae (Kisumu), 5h 30min for An. gambiae (Goden, local strain), and 4h for Ae. aegypti for both the local and sensitive strain. These laboratory results suggest that MAA is a good repellent against the three mosquito species. During these field tests, a total of 3979 mosquitoes were caught. In this population, anophelines represented 98.5%, with culicines (Aedes) making up the remaining 1.5%. Among anopheline mosquitoes, 95% belonged to the An. gambiae complex, followed by Anopheles funestus and Anopheles pharoensis. The median CPT of 20% DEET and MAA were similar (8h) and much longer than that of the negative control (2h). CONCLUSIONS: Results from the present studies showed that MAA offers high protection against anophelines biting indoors and outdoors and could play an important role in malaria prevention in Africa.